The present invention relates to a controller for a heat power plant, and more particularly to a controller for a heat power plant which can minimize an effect to the heat power plant when trouble occurs in the controller.
The heat power plant which has a social mission to stably supply power must be operated with a high reliability. To this end, plant equipments as well as a plant controller are designed for high reliability and the controller is designed to prevent stop of the plant even if the controller stops by failure. For example, in U.S. Pat. No. 4,347,564, the controller is partially duplicated so that a host computer is used when a master controller fails. In Japanese unexamined patent publication No. 50-143,989, a so-called one-to-n backup system is used in which a backup sub-loop controller which is normally not used is started when a normal sub-loop controller fails. In such multiple systems, even if trouble occurs in one controller, the heat power plant can continue operation and a highly reliable controller is provided. However, since the multiple system needs at least one redundant controller of the same function, the cost of the controller system is increased.